The proposed research is a study of the origins and development of ethnic communities and the relative persistence of ethnicity as an influence upon urban life in contemporary America. We plan to focus, in particular, upon the interaction between the sociocultural heritages of immigrant groups and the changing structural conditions of American cities. The research strategies include the examination of historical records and census data, and the collection of data from a contemporary sample survey and detailed "life-history" interviews, permitting the analysis of the relationships among individuals, institutions, and communities. Special attention will be given to the relationship between occupation and residence in order to examine the influence of the changing ecology of the industrial metropolis upon ethnic communities.